Where does “caetaceum” come from?

caetaceum (Latin) comes from Latin cētus, from Ancient Greek κῆτος — whale, sea monster; abyss.

Ancestry of “caetaceum”, step by step

Step	Language	Word	Meaning
1	Latin	cētus	Any large sea-animal, such as a whale, shark, seal, dogfish, dolphin, or tuna, or a sea monster
2	Ancient Greek	κῆτος	whale, sea monster; abyss